1. Field of the Invention
The present invention relates generally to a set of instruments having a distal tapered configuration for facilitating insertion of the instruments into a human body.
2. Description of the Related Art
Cannulas are used in surgical procedures to access tissue of the human body. To assist in the insertion of the cannula into the tissue, an instrument such as a stylet is inserted into the cannula to function as a guide for the cannula. Typically, the stylet has a diameter less than the diameter of the cannula, creating a stepped transition between the cannula distal end and the stylet. One problem encountered when using a conventional cannula and stylet is that the stepped transition between the cannula and stylet impairs the insertion of the instruments into the surrounding tissue because of the increased resistance encountered upon moving the stepped transition against the surrounding tissue. Therefore, there exists a need for an instrument set having a reduced surface profile in the transition between the distal end of the cannula and the inner instrument when the inner instrument extends from the distal end of the cannula so as to facilitate insertion of the instrument set into a patient and minimize disruption to the tissue of the patient.
Another problem associated with conventional cannulated instrument sets is that the distal end of a stylet when inserted together with the cannula protrudes a distance from the distal end of the cannula that is insufficient to optimally guide the instrument set into the surgical site of a patient, or optimally penetrate the tissue. Therefore there exists a need for an instrument set that when used with a stylet, will provide the surgeon with increased guidance for inserting the instrument set into the surgical site of the patient while reducing the effort needed for the instrument set to penetrate the tissue.